During April-June 2017, CDC, FDA and state public health partners investigated an outbreak (1704MLJEG-2) of 151 Salmonella Enteritidis infections reported from 36 states. Patients ranged in age from <1 to 97 years. Among 114 patients with available information, illness onset dates ranged from March 2, 2017 to May 23, 2017. Thirty one people were hospitalized. No one died.

Epidemiologic exposure information was available for 63 patients. Among these patients, 47/63 (75%) reported eating romaine lettuce in the week prior to illness onset compared to 46% of US residents surveyed for the 2006-2007 FoodNet Population Survey. No other exposure reached a similar level of statistical significance.

FDA and states initiated an informational traceback for single cases and restaurant clusters with exposure to romaine lettuce and whole head lettuce. The lettuce supplied to the points of service converged to two major leafy green companies. However, traceback of romaine lettuce did not converge on a single brand, supplier, or growing region.